The long-term goal of this proposal is to understand the mechanism of action of calcium signaling pathways in airway smooth muscle in order to identify novel bronchodilators for the clinic. The immediate goals for this proposal are twofold. The research will provide an understanding (at the cellular level) of how a novel bronchodilator, UCL 1684, modulates SK channels and causes airway smooth muscle relaxation. The research will determine the mechanism by which SR SK potassium channels affect sarcoplasmic reticulum and cytosolic calcium load, excitability and contractility of ASM cells using calcium imaging and electrophysiology of airway smooth muscle cells. Second, the research will investigate UCL 1684 efficacy as a bronchodilator in vivo in animal models of asthma and models of 2 agonist tachyphylaxis. The approach will be to use whole animal plethysmography, and the forced oscillation techniques on asthmatic mice to evaluate UCL 1684 effects on airway severity and airway resistance, respectively. In addition, the experiments will examine UCL1684 effects on remodeling during asthma with a particular emphasis on its effects on airway muscle remodeling.